Method for preparing microscope slides by rotating during coating

ABSTRACT

A plurality of glass slides having specimens such as blood smears disposed thereon are prepared for microscopic viewing by an apparatus which automatically applies preparation solutions to the slides such as stains and buffers and thereafter automatically drys the completed slides. The staining and buffering solutions are deposited evenly over the surfaces of the slides carrying the specimens by a timed operation of one or more electro-mechanically actuated aerosol dispensers which produce fine sprays of the desired preparation solutions. Simultaneously with the generated spray, the plurality of slides are rotated at a relatively slow rate to cause a uniform distribution of the spray particles on the slide surfaces. Following the staining and buffering mode, an automatic drying mode is initiated in which the plurality of slides are rotated at a relatively higher speed for a timed interval after which the apparatus automatically turns off and the completed slides may be removed from the apparatus.

This is a division, of application Ser. No. 565,149, filed Apr. 4, 1975,now U.S. Pat. No. 4,004,550; which is a continuation of Ser. No.419,947, 11/29/73, now abandoned.

BACKGROUND OF THE INVENTION

The present invention generally relates to a method and apparatus forpreparing specimens on glass slides suitable for viewing under highmagnification such as by a microscope.

Although the present invention has generally utility in preparing alltypes of microscope slides and slide specimens, there is a particularneed for a more automatic and efficient process for preparing biologicalor medical specimens for diagnosing and treating medical conditions. Toa large extent modern medical practice depends upon the laboratory testswhich may be conducted on specimens obtained from the patient.

The analysis of blood samples from the patient is an extremely valuabletool. Usually the blood specimens are analyzed by preparing blood smearson microscopic slides and subjectinfg the blood smear specimen tomicroscopic viewing. For this purpose in order to prepare a blood smearfor lab testing, fresh whole blood is smeared on to a standardlaboratory glass slide and thereafter a staining solution is applied tothe smear in order to bring out or enhance the viewability thereof.Following the staining operation, a separate process is performed toapply a buffering solution which fixes or stabilizers the stainedspecimen so that it remains in a relatively permanent state during themicroscopic analysis. Still another operation must be performed afterthe buffering, the that is to place the slides in an oven or the like toevaporate any remaining liquid and thus to dry the blood smear, stainsolution and buffering solution. This completes the preparation process.

Although in small laboratories where only a few slides are prepared at atime, the foregoing individual operations may not be toodisadvantageous. However in much larger laboratories for example thoseassociated with a large metropolitan hospital, the foregoing techniqueof preparing slides is wholly inefficient, occupying too much of thelaboratory technician's time and tending to produce nonuniformity in theprepared slides. Additionally, the increased handling of the glassslides typically necessitated by the various individual processingsteps, to leads to more accidental breakage of the glass slides and lossof specimens.

SUMMARY OF THE INVENTION

In general, it is an object of the present invention to overcome theforegoing disadvantages associated with conventional processing ofspecimen slides. There have been previous attempts to automate the slidepreparation such as exemplified by U.S. Pat. No. 3,352,280 issued to R.Hughes et al.

However, this and other heretofore proposed apparatus have not met withwide acceptance. It is believed that the reason for this lies in thecomplexity, expense, susceptibility to malfunction, and in general theinability of these previous machines to accomplish the underlyingobjective, that is to more efficiently and more economically preparespecimen slides. For example, the apparatus disclosed in U.S. Pat. No.3,352,280 attempts to apply the stain and buffering solution bydribbling it in liquid form on to a rapidly rotating surface adjacentthe individual specimen slides. The rapidity of rotation of the slidesis said to force the stain and buffering solution outwardly undercentrifugal force to apply layers of these liquids to the slidespecimens. However, it is not believed that such an apparatus is capableof producing suitably uniform staining and buffering.

The method and apparatus according to the present invention overcomesthese and other shortcomings of the prior art as will become apparent tothose skilled in the art from a consideration of the following detaileddescription and appended drawings of a few particular embodimentsthereof.

IN THE DRAWINGS

FIG. 1 is an overall perspective view of the apparatus for automaticallypreparing slides in accordance with the present invention.

FIG. 2 is an assembly view also in perspective showing some of theprincipal components of the apparatus of FIG. 1.

FIG. 3 is a vertical cross-sectional view taken generally along a centerplane of the apparatus shown in FIG. 1.

FIG. 4 is a detailed schematic diagram of the control circuitry employedin the apparatus of FIGS. 1 through 3.

FIG. 5 is a schematic representation of an alternative embodiment of thepresent invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIGS. 1 through 4, the present invention provides amethod and apparatus for automatically preparing microscope specimenslides. More particularly, an apparatus indicated at 11 serves toreceive a plurality of specimen slides 12, which may be of a standardrectangular shape glass construction and on which a specimen or othersample has been deposited.

For the particular embodiments disclosed herein, slides 12 are describedas receiving a blood smear specimen, and the solutions automaticallyapplied by apparatus 11 are intended for this particular type ofspecimen. It will be apparent however, that the present invention may beused for a variety of different slide specimens and the solutionsapplied for staining, buffering or other purpose may vary depending uponthe requirements of the particular specimen.

Apparatus 11 is constructed to include a rotatable slide carrier meansfor receiving and holding a plurality of the specimen slides 12. In thisinstance, the carrier means is provided by a turntable 13 mounted forrotation inside a bowl shaped chamber 14 defined by a bowl structure 16.

Turntable 13 is rotatably driven by an electrical motor drive means,here provided by a motor 17 having a vertically oriented drive shaft 18connected to an overlying turntable hub 19.

Turntable 13 is formed or provided with a plurality of slide holdermeans for receiving and removably holding a corresponding plurality ofthe specimen slides 12. In this instance, the slide holder means areprovided by a plurality of radially extending slots or recesses 21formed in an upper face 22 of turntable 13 for receiving a lower edge 23of each of slides 12 when disposed with their longitudinal axes in thehorizontal plane and thus parallel to surface 22.

By mounting slots 21 along the radii like the spokes of a wheel, thenumber of slides 12 which may be accommodated by apparatus 11 ismaximized for greatest efficiency. Furthermore, as more fully disclosedherein, this orients the faces of slides 12 advantageously for receivingthe applied preparation solutions.

To retain the preparation solutions within the apparatus duringoperation thereof and moreover to provide a generally enclosed chamber14 within which the slides are rotated, a closure or lid 24 may beprovided mating with an upper peripheral edge 26 of bowl shapedstructure 16 as illustrated. If desired, lid 24 may be of a transparentmaterial to permit viewing of the slides 12 during preparation.

Apparatus 11 further includes one or more controllable spray dispensermeans for injecting a mist or spray 28 of slide preparation solutiontoward or in the proximity of plurality of rotating slides 12. The spray28 which is developed in this manner intercepts the slides 12 which aresimultaneously rotated by turntable 13 causing the solution to beuniformly deposited on the surfaces of the slide. Preferably, turntable13 is rotated in a direction with the side of each slide 12 having thespecimen thereon leading the nonspecimen or nonprepared slide surface.For example in this case with turntable 13 rotating in a directionindicated by arrow 29, the specimens would be placed on the leadingsurfaces or sides 31 rather than on the trailing surfaces 32 so that thespecimen sides 31 intercept the spray 28 causing most of the sprayparticles to be deposited on the desired surface.

More particularly, the spray dispenser means is preferably provided byan aerosol spray assembly 33 which includes both an aerosol propellantand a slide preparation solution. In this particular embodiment, aseparate and controllable aerosol propellant can 34 is provided incombination with a separate solution container 36, both of which areconnected by conduit means 37 to develop a solution spray 28 of thecontents of container 36. Thus, aerosol propellant can 34 which merelyserves to provide a source of propellant gas, and solution container 36together with conduit means 37 provide the spray assembly 33.

Spray assembly 33 is automatically rendered operable at the proper timeand for the proper duration by an electrically operated spray actuatormeans. In this instance, the actuator means is provided by anelectromagnetic solenoid assembly 38 having a plunger 39 selectivelydriven to engage and depress an actuator valve 41 of aerosol can 34.Actuator valve 41 may be of a standard type in which a downward forcethereon releases the propellant from can 34 and allows it to escapeunder pressure into conduit means 37.

Conduit means 37 includes a first conduit section 42 which may beextended into chamber 14 through an aperture or window 43 of structure16 as illustrated, and a second conduit section 43 which joins section42 at an aspirating or suctioning junction 44 serving to aspirate theliquid contents of container 36 into the stream of gas flowing towardchamber 14 through conduit section 42. The arrangement of propellant can34, conduit means 37 and container 36 are known per se and constituteonly one form of the spray assembly 33 which may be employed in thepresent invention.

In the presently disclosed embodiment, the preparation solution providedin container 36 includes both a staining solution and a bufferingsolution for preparing blood specimens. By this arrangement, thestaining and buffering or fixing of the slides 12 is accomplished by thesame spray 28 and solenoid 38 may be operated just once during anapparatus cycle.

On the other hand, one or more preparation solutions may be provideddirectly within an aerosol can 34 of the type including both the appliedsolution and the aerosol propellant in a wellknown manner. It has beenfound, however, that certain solutions if provided within the aerosolcan 34 tend to freeze under the evaporating effect of the aerosol liquidpropellant, and in such case it is possible to provide the solution in aseparate container such as the here illustrated container 36.

Also, in the embodiment of FIGS. 1 through 4, the stain and bufferingsolutions are applied simultaneously in a single spray, whereas these orother preparation solutions may be applied separately and sequentiallyby an alternative embodiment of the present invention to be describedmore fully herein connection with FIG. 5.

To coordinate the functions of apparatus 11 an electrical control meansis provided including timing means connected to the motor drive meansprovided by motor 17 and connected to the spray actuator means providedby solenoid 38. This timing means serves to provide a timed sprayinginterval in which the motor 17 and solenoid 38 are jointly energized andthereafter a timed rotating interval in which only the motor drive meansin the form of motor 17 is energized. More particularly, the controlmeans including the timing means provides for simultaneously drivingmotor 17 and energizing solenoid 38 in a spray dispensing mode at thetermination of which only motor 17 is energized during a drying mode.Moreover, during the spray mode, motor 17 is energized at a relativelyslow rate of rotation such that turntable 13 and the slides 12 carriedthereby are moved at an optimum rate for intercepting the solution spray28 to receive a uniform deposit thereof on the specimen side 31 of theslides. However, after the spray dispensing mode has terminated andsolenoid 38 is de-energized to terminate the aerosol spray, then adrying mode is entered into which motor 17 is energized at asubstantially greater rate of rotation.

Although the exact speeds of rotation of motor 17 and turntable 13during the spray and drying modes is not believed critical, a speed oraround of 40 rpm for the spraying mode and a speed of around 200 rpm forthe drying mode has been found satisfactory. The relatively lower rateof rotation during the spraying mode is desirably fast enough to provideuniform deposition of the spray solution and yet slow enough to preventthe spray from being blown out of contact with surfaces 31 of theslides. The drying speed on the other hand should develop sufficient aircurrents to speed the evaporation and drying process. Typically, thespraying speed will be adjusted to an optimum level in theabove-indicated range and the drying speed will be approximately 3 to 7times greater than the spraying mode speed.

Finally, the control means of the present invention provides forautomatically shutting off the apparatus after a timed interval of thedrying mode. This restores the apparatus to an initial state, with theturntable 13 stopped so that lid 24 may be opened and the fully preparedslides withdrawn from the apparatus.

Although the circuitry for the control means may take many differentforms, in this particular instance, the disclosed apparatus utilizes thecontrol circuit shown in FIG. 4. In conjunction with the circuit of FIG.4, a manually operated power switch 51 may be provided as illustrated inFIGS. 1 and 4 for selectively applying or interrupting a line voltage tothe apparatus available over lines 52 qand 53, each of which may beprovided with a fuse 54. Line 53 is connected directly to a control line56, one terminal 57 of motor 17 and one terminal 58 of solenoid 38 asillustrated.

The other line 53 is connected through power switch 51 as illustrated inFIG. 4 to a push-button start switch 59, which may be mounted along withswitch 51 on apparatus 11, to a contact 61. Also, switch 51 connectsline 53 to a relay contact 62 of a relay 63. Relay 63 is illustrated inan unenergized condition and may be latched to an energized condition bymomentarily operating switch 59 to energize a relay coil 64 connected toswitch contact 61 with the circuit to the opposite end of coil 64 beingcompleted through a set of relay contacts to control line 56 connectedto line 52. Once energized, relay 63 is latched to the energized statethrough contact 66 and 62 connecting line 53 to contact 61 and thus toone side of relay coil 64.

Simultaneously with the energization of relay 63, the normally opencontacts 67 and 68 are closed thus supplying line voltage from line 53to a junction 69 of a first relay timer 71. Relay timer 71 includes arelay coil 72 which must receive an applied voltage thereacross for atimed interval before the contacts of relay timer 71 are operated. Thus,initially upon receiving the line voltage at junction 69, relay coil 72remains unenergized and the normally closed contacts 73 and 74 remainclosed to energize motor 17 through timer contact 73, variable resistor76 and a second terminal 77 of the motor, and to actuate solenoid 38 viacontacts 74 and a second terminal 78 of the solenoid.

This condition of the circuit corresponds to the spraying mode ofapparatus 11 described above in which motor 17 is energized at arelatively low rate of rotation and solenoid 38 is concurrentlyenergized to inject the solution spray 28 into chamber 14.

After a predetermined time delay which may be adjusted by appropriateselection of relay timer 71, coil 72 is energized causing normallyclosed contacts 73 and 74 to open and normally open contacts 81 and 82to close. Contacts 81 are not used in this instance, however normallyopen contacts 82, now closed, apply the incoming line voltage availableat junction 69 to a junction 83 of a second relay timer 84. Relay timer84 operates in a similar manner to timer 71, and a line voltage must beapplied across a coil 86 thereof for a predetermined time before thecontacts of timer 84 are operated.

Before coil 86 of timer 84 is operated, the normally closed contacts 87thereof maintain relay 63 energized by connecting a line 88 through thenormally closed contacts 87 to a junction 89 which in turn is extendingback to connecting line 56 to the other incoming line 52 of the linevoltage.

Also, timer 84 through normally closed contacts 91 energizes a coil 92of motor drive relay 93. Relay 93 through its normally open contacts 94applies the line voltage available at lines 52 and 53 directly acrossthe first and second terminals 57 and 77 of motor 17 for energizing themotor at its full rotational rate. Thus during this mode, motor 17 isoperated at a speed appropriate for the drying mode. Also, it is notedthat relay timer 84 serves to time the drying interval.

After a predetermined elapsed time for the drying mode, relay timer 84becomes energized via coil 86 causing normally closed contacts 87 and 91to be opened. The opening of contacts 87 unlatches the previouslylatched relay 63 while the opening of contacts 91 de-energizes motorrelay 93 thus shutting off motor 17. This terminates the variousoperating modes of the apparatus and restores the control circuitry toits original or starting condition ready to receive another start viapush-button switch 59.

The control circuitry of FIG. 4 may all be mounted in a control unit 96disposed within an annular base structure 97 serving to support bowlstructure 16 and motor 17 as illustrated in FIG. 3. Switches 51 or 59may be mounted as shown on base structure 97 for convenient manualaccess. A plug 98 may be provided for connecting the apparatus to astandard utility outlet for energizing lines 52 and 53.

For receiving and supporting aerosol spray assembly 33, a base extension101 may be provided extending radially outwardly from a lower supportsurface 102 of base structure 97 and having an upstanding portion 103extending upwardly adjacent assembly 33 for supporting solenoid 38 in anoverlying relation to aerosol propellant can 34. Upstanding portion 103may have a spring clip 104 mounted thereto for securement of aerosol can34 as illustrated. Base extension 101 may be fastened to base structure97 by suitable means as illustrated at 106, and the electrical wiringbetween control unit 96 and solenoid 38 may be provided by a flexiblecable 107.

With reference to FIG. 5, an alternative embodiment of the presentinvention is illustrated in which a plurlity of control spray dispensermeans are mounted adjacent the periphery of a rotating slide carriermeans. In this instance, the plurality of spray means may be constructedsimilar to spray assembly 33 and solenoid 38 and mounted at a pluralityof circumferentially spaced spray stations such as indicated at 111,112, 113 and 114. Each of these stations may be constructed similarly tothe single spray station of assembly 33 and solenoid 38 shown in FIGS. 1through 4.

To inject the plurality of sprays into a chamber 14' of bowl structure16' as shown in FIG. 5, there are a plurality of spray apertures orwindows 43', one for each spray station. Other than these modifications,the apparatus of FIG. 5 may be similar to that shown in FIGS. 1 through3, in that a turntable 13' is provided with a plurality of radial slots21' for accommodating the correponding plurality of specimen slides 12'.

It is an advantage of this embodiment that two or more spray stationssimilar stations 11 - 114 may be provided for applying differentpreparation solutions either concurrently or according to apreprogrammed sequence. For example if desired, two such spray stationsmay be provided, one for introducing a stain spray while a secondstation is provided for injecting the buffering solution. If theplurality of spray stations 111 - 114 are formed similar to theembodiment of FIGS. 1 through 3, each will be provided with a separatesolution container similar to container 36 of FIGS. 1 through 3, forstoring and dispensing a different solution or mixture of solutions.

Each of the individual spray stations 111 - 114 may be provided with adifferent timing means as part of the electrical control means, such asthe here illustrated timers 121, 122, 123 and 124 for selectivelyenergizing the solenoid actuators associated with stations 111 - 114,respectively. That is each of timers 121 - 124 may, if desired,individually control the time interval during which the associated sprayassembly is actuated.

With references to the overall control circuit shown in FIG. 4, thevarious timers 121 - 124 may be triggered or started from a control line74 available from the normally closed contacts 74 of relay timer 71.That is each of the separate inputs 126, 127, 128 and 129 may be jointlyconnected to a control line 74' corresponding to lines 75 of FIG. 4. Inthe case of the embodiment of FIG. 5, the control line 75' originatingfrom the normally closed contacts 74 of relay timer 71 would not beextended directly to and for controlling a solenoid as it is in theembodiment of FIG. 4. Rather, control line 75' is extended jointly tothe inputs 126 - 129 of timers 121 - 124 for controlling the associatedactuator solenoids only through the respective timers. A return path maybe provided for the timer circuits as indicated by return line 131connected back to motor timing and energizing circuit 132 which wouldcorrespond substantially to the circuit in FIG. 4 except for thedeletion of solenoid 38. In other words, the two connecting lines ofFIG. 4 extended to and for driving the solenoid 38 may instead providethe output lines 75' and 132 for activating the various timer circuits.Of course, this is only one possible arrangement for the timing of spraystations 111 - 114, and many suitable alternative arrangements for thetimer circuitry will occur to those skilled in the art. This particulararrangement allows the overlapping or concurrent operation of the spraysassociated with the various stations. For example, station 111 mayprovide a solution spray which is timed by timer 121 and which lasts forthe full duration of the spray mode, while stations 112 - 114 may occurfor brief intervals during the spray mode and thus have a shortconcurrent period with the spray from station 111.

In general, it will be seen that any number of different spray modes andcombinations thereof may be provided by the embodiment of FIG. 5. Thus,microscope slides which would otherwise involve a considerable number ofseparate steps during the preparation thereof, are quickly andefficiently prepared by this embodiment of the invention.

While only a limited number of embodiments of the present invention havebeen disclosed herein, it will be readily apparent to persons skilled inthe art that numerous changes and modifications may be made theretowithout departing from the spirit of the invention. Accordingly, theforegoing disclosure and description thereof are for illustrativepurposes only and do not in anyway limit the invention which is definedonly by the following claims.

We claim:
 1. A method of applying the same quantity and a uniformdistribution of a solution onto the faces of a plurality of microscopeslides having specimens disposed thereon for subsequent microscopicviewing, comprising:rotating said plurality of slides about a commonvertical axis such that the face of each slide is in a radial plane;simultaneously producing an atomized spray of said solution; depositingsaid atomized spray uniformly on the faces of the slides during therotating of the slides.
 2. The method defined in claim 1 wherein thespeed of the rotating slides is such as to not cause the depositedsolution to move across the face of the slide due to centrifugal forcewhich would cause an uneven distribution of the solution upon the faceof the slide.
 3. The method defined in claim 1 wherein a plurality ofatomized sprays of different solutions are produced and deposited one ata time on the faces of the slides during the rotating of the slides. 4.The method defined in claim 1, wherein the rotating of said plurality ofslides during the spray depositing is relatively slow, and including thestep of, subsequent to the producing and depositing of said atomizedspray, rotating said slides at a relatively faster speed so as to effectthe drying of said deposited spray but not so as to cause the depositedspray to be moved across the slide by centrifugal force.
 5. A method forautomatically preparing microscope specimen slides having specimensdisposed thereon comprising the steps of:automatically rotating aplurality of specimen slides by a motor driven turntable; said pluralityof slides are rotated about a common axis such that the face of eachslide is in a radial plane extending from the axis; electricallycontrolling an aerosol spray producing assembly to apply a slidepreparation solution to the specimen slides during rotation thereof; andautomatically drying said specimen slides after applying said solutionspray be terminating said spray and automatically rotating said motordriven turntable at a higher rate of rotation.